In the prior art, the slide-proof structure is installed between an outer wall of a half shaft gear and a planet frame of a differential mechanism. The left gear, right gear, and planet gear may be umbrella form gears or surface gears.
In U.S. Pat. No. 5,472,385, a slide-proof structure is disclosed. The slide-proof structure is installed between a half shaft gear and a planet frame of a differential mechanism, that is at a backside of a half shaft gear and a wall of a planet frame facing to the backside of a half shaft gear. Thus, the slide-proof structure has a larger volume and the cost is high. For a longer time, the frictions between the left gear, the right gear and the slide-proof sheet become great so as to affect the efficiency of the differential mechanism.